Adsorbent material and the manufacture and application thereof



Patented May 26, 1925.

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EVAN c. WILLIA S, or

I ADSORBENT MATERIAL AND THE MANUFACTURE AND APPLICATION THEREOF.

1T0 Drawing.

To all whom it concerm: Be it known that I, EVAN CLIFFORD WIL- LIAMs, asubject of the King ofGreat Britain, residing at Huddersfield, inthecounty 5 of York and Kingdom of England, have invented certain new anduseful Improvements in Adsorbent, Materials and the Manufacture andApplication Thereof, of which the following is a specification.

This invention relates to an improvement in adsorbent materials and inthe manufacture and application thereof.

g It is known that silica can be obtained in the gel form e. g. bytreating sodium silicate solutions with acid, washing with water with orwithout dialysis and drying the washed gel at ordinary temperature invacuo or at a raised temperature- Such a dried gel is known to possesspowerful adsorbent properties and it has been proposed to use it forseparating the various constituents of gases or liquids.

' When such a gel is prepared according to known methods, even afterprolonged washing with water, it is found that on heating to atemperature of say 900 C. the adsorptive properties of the gel arematerially reduced. It is one object of my invention to overcome thisdisadvantage since 3 vigorous heating of the gel is most desirable forpurposes of revivification.

I have discovered that a gel which is practically free from alkali metalsalts can be so heated to say 900 C. with safety.

Apparently the traces of alkali metal salts present in gels hithertoprepared are capable of causing some catalytic acceleration of thecrystallization of the silica gel on heating and this effect isenormously reduced in absence of alkali metal salts.

The invention further includes the separation of constituents fromfluids e. g. liquids or gases, by the aid of silica gel containingpractically no alkali metal salts and the revivification of the gel byheating to a high temperature.

The invention specifically includes one method of obtaining such a gel,namely by the hydrolysis of silicon compounds in ab- 50. sence ofsoluble and non-volatile bases, but the gel free from alkali metal saltsand 'possesing the desirable property already Application flied December8, 1923. Serial No. 679,499.

mentioned is considered to be a broadly novel product.

Example.

Silicon chloride is poured into water with.

The gel is washed and then carefully dried at 100 C. with heat though itmay be dried direct (without washing) if desired, thus the drying maylast 12-24hours; the temperature may then be slowly raised to 400 C.

Care is taken not to destroy the microstructure of the gel and thus toafl'ect its adsorptive properties.

The product is practically free from alkali metal salts such as, sodiumchloride or sulphate. Traces of such salts are undesirable since theytend to accelerate crystallization of the amorphous silica. -Hence thegel obtained by my process can be heated to a higher temperature withoutdestroying its adsorptive properties e. g. up to 900 to 1000 C.

Silica gel free from alkali metal salts (whether prepared as abovedescribed or in other manner) can be used for adsorbing constituentsfrom a liquid or a gas and I find that in treating coal gas or coke ovengas' the silica gel is contaminated by tar, or polymerized'products e.g. of dio'lefinic nature and thus it must be revivified by heating in anoxidizing atmosphere. The gel produced according to my invention isparticularly valuable for-treating such gases since I can revivify it byheating to a temperature sufiicient to burn oil. such polymerized bodieswithout seriously affecting the adsorptive properties. Silicon sulphideor various silicon halogen compounds can also be used as raw materials.

I declare that what I claim is T1. Adsorptive silica gel free fromalkali metal salts.

2. Adsorptive silica gel so free from alkali metal compounds. that itcan be repeatedly heated to about 900 C. without In witness whereof, Ihave hereunto substantial diminution of its adsorptive' signed my namethis 22 day. of November powers. 1923, in the presence of twosubscribing 5 1611 process of producing dryhlsiliga. witnesses.

e w 0 com rises mlxm s1 mm c on e vith water wit h such agita tion andin such WILLIAMS proportions that a. gel is obtained on stand-Witnesses:

mg and then drymg said gel slowly by HAROLD E. Po'rrs,

heating. v E'. DREW BARTLM'I.

